Question

When strongly heated orthoboric acid gives

Answer 1

1) boric acid on heating above 170C gives metaboric acid 
                          

                            170°C
*)         H3BO3   ------------------>  HBO2      +   H2O 
        boric acid                            metaboric acid

2)  on further heating above thn 300°C give tetraboric acid 
                                       300°C
*)   4HBO2    ----------------------------------> H2B4O7  + H2O
   metaboric acid                                        tetraboric acid

3)  on further heating give boron trioxide

*)  H2B4O7--------------------------->  2B2O3   + H2O
  tetra boric acid                             boron trioxide

HOPE IT WILL HELP IF HELP THN PLZZ MARK AS A BRAINLEIST ^_^